Abstract
BackgroundTheory predicts that parasites can affect and thus drive their hosts’ niche. Testing this prediction is key, especially for vector-borne diseases including Chagas disease. Here, we examined the niche use of seven triatomine species that occur in Mexico, based on whether they are infected or not with Trypanosoma cruzi, the vectors and causative parasites of Chagas disease, respectively. Presence data for seven species of triatomines (Triatoma barberi, T. dimidiata, T. longipennis, T. mazzottii, T. pallidipennis, T. phyllosoma and T. picturata) were used and divided into populations infected and not infected by T. cruzi. Species distribution models were generated with Maxent 3.3.3k. Using distribution models, niche analysis tests of amplitude and distance to centroids were carried out for infected vs non-infected populations within species.ResultsInfected populations of bugs of six out of the seven triatomine species showed a reduced ecological space compared to non-infected populations. In all but one case (T. pallidipennis), the niche used by infected populations was close to the niche centroid of its insect host.ConclusionsTrypanosoma cruzi may have selected for a restricted niche amplitude in triatomines, although we are unaware of the underlying reasons. Possibly the fact that T. cruzi infection bears a fitness cost for triatomines is what narrows the niche breadth of the insects. Our results imply that Chagas control programmes should consider whether bugs are infected in models of triatomine distribution.
Highlights
Theory predicts that parasites can affect and drive their hosts’ niche
The two species whose inter-centroid distances were higher were T. barberi and T. mazzottii, Fig. 1 Potential triatomine distribution in Mexico and surrounding areas for Triatoma barberi (a), T. dimidiata (b), T. longipennis (c), T. mazzottii (d), T. pallidipennis (e), T. phyllosoma (f) and T. picturata (g) the latter exceeding a standard deviation from the mean of centroid-random point distances
Since not all bug species show the same trend in niche use for infected and non-infected animals, we hypothesize that this pattern may be seen as the different aspects of a co-evolutionary arms race between T. cruzi and triatomines
Summary
Theory predicts that parasites can affect and drive their hosts’ niche Testing this prediction is key, especially for vector-borne diseases including Chagas disease. For example, this has been widely evidenced by the close evolutionary radiations between pathogens and hosts in many different taxa [2,3,4]. Parasites can modulate their host’s niche in two ways [5]. Villalobos et al Parasites Vectors (2019) 12:240 life histories (for example, a parasite with an intermediate and definitive host), and whose distribution is expected to be narrower than that of their hosts [11]. According to a niche restriction test, one would predict that infected hosts will have a more restricted ecological niche than non-infected hosts
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